Answer:
d) Interaction between Arg and Lys side chains at a pH of 7, assuming standard pKa values for Arg and Lys.
Step-by-step explanation:
Arginine and Lysine are basic amino acids. They play same role in various membrane proteins. They both have high aqueous values which give rise to high electrostatic interaction. The interaction is mainly in the cations of the side chains. They both are heterologous secreted proteins which plays role of metabolite.